Damper assemblies in HVAC air ducts include a movable damper capable of Hocking or diverting air, or other gases, passing through the interior of the duct, intended to heat or cool the building in which it is located. It is often desirable to manually control the damper, and for this purpose a control shaft is attached to the damper and extends through an opening in the duct wall to the exterior of the duct, A handle is fitted onto the outer end of the control shaft, and is secured to the control shaft by, e.g., a nut.
Generally, such damper assemblies contained within short sections of a duct are assembled at the factory, to insure a close fit in the wall opening to prevent loss of air pressure and are commonly available in complete units. The control shafts on the prefabricated assemblies extend out from the outer surface of the duct only a short distance. However, it is often desirable, as an energy saving method, to have the entire length of the air duct, including the damper assembly portion, wrapped in insulation; in such a situation, usually the factory installed control shaft does not extend out beyond the insulation layer, interfering with the operation of the handle on the control shaft, to operate the damper. Many attempts have been made to simply extend the length of the shaft for the handle so that the handle can easily move beyond the thickness of the insulation. For example, two different concepts are shown in U.S. Pat. Nos. 4,646,715 and 6,035,849. They have all had the problems of undue complexity, because of the number of parts that the ultimate installer was required to handle.
Accordingly, it is an object of the present invention to provide a product that will simplify the end user/installer's work in adding a unitary extension to the damper apparatus that will effectively extend the control shaft of a damper assembly beyond the layer of insulation, permitting a certain amount of regulation as to the length of the control shaft.